Apparatus for casting dental restorations



June 3, 1941. HOR ES 2,421,698

APPARATUS FOR CASTING DENTAL RESTORATIONS Filed Jan. 4, 1946 INVENTOR havma M03055 ATTORNEY Patented June 3, 1947 APPARATUS FOR CASTING DENTAL RESTORATIONS Irving Hordes, Yonkers, N. Y.

Application January 4, 1946, Serial No. 639,078

2 Claims.

My invention relates particularly to apparatus for use in the casting of dental restorations, that is, in forming a bridge, an artificial tooth or part thereof, such as an inlay crown and the like, and other dental structures.

A primary object-of my invention is to produce a novel apparatus which is particularlysuited for casting dental restorations using a plastic or other suitable material as the casting material.

Another object is to provide means for keeping the acrylic clean.

Another object is to provide means for preventing particles of investment material entering into the mold.

Another object is to eliminate the necessity for a protective coating on the sprue.

Another object is to provide apparatus of this kind that is easily manipulated, inexpensive, comparatively simple in construction and readily adjustable to meet any requirement in the casting of dentalrestorations.

Other objects and advantages of the invention will be apparent from the description thereof to follow taken in connection with the accompanying drawing in which- Fig. l is a Vertical sectional view of my improved apparatus showing the flask in position on its frame or support and with the sprue forming members in position and carrying a wax pattern which forms the mold'in the investment.

Fig. 2 is a top plan view of the parts shown in Fig. 1.

Fig. 3 is a detail view of the outer sprue forming member.

Fig, 4 is a detail view of the inner sprue forming member.

Fig. 5 is a detail View of the inner sprue memher and pin and the wax pattern supported thereby.

The plastic used for making dental restore.- tions should be in a soft but viscous state, that is, about the consistency of putty or a thick paste. Plastic in this condition may be obtained or pre' pared in two Ways, Powdered or granulated plastic in its cured or polymeric form is mixed with a portion of the plastic in liquid or monomeric form in a manner known to the dental technician in preparing plastic to be used for forming dental plates and the like. The viscous plastic may be obtained also by using polymeric plastic in powdered, granular or biscuit form and heating it until it has the proper viscous consistency.

' like base member I5 which is provided with a central opening 16. An inner sprue member I! projects through the opening l6 and is provided with a shoulder portion adapted to engage the shoulder of the sleeve l2 and with a projecting neck portion l8 extending outwardly of the restricted opening in said sleeve. An opening I!) extend centrally through said sprue member IT.

The wax pattern I 0 is mounted upon the pin H, after which the latter is inserted into the opening Iii and held in position by a spot of wax which connects said pattern with the upper edge of the neck l8 of the member H. The wax pattern is thus held spaced from the end of the outer sprue member l2.

The flask 20 is a split or two-part type of flask comprising a lower mold section 2| and an upper mold section 22, as shown in Fig. 1, said sections having interlocking flange portions on their edges and may have pry-notches on said edges to facilitate separation of the sections. The mold sections have tapered inner walls in opposed relation.

The sections of the flask are held in superimposed position by means of a clampin device consisting of a frame 23 preferably formed of a casting having a rectangular base 24 with an upwardly extending post 25 at each corner. Between the posts 25 on each side is another guide post 26 having a screw threaded upper end, which posts 25 project above the posts 25. Slidably and detachably mounted on the posts 26 is a plate 21. The plate is formed with end openings for receiving the posts 26 and with a central opening 28 adapted to register with the openings in the flask sections. The plate rests on the upper edge of the flask. Nuts 29 on the posts above the plate clamp the flask sections together and hold them against displacement on their support.

In using my improved apparatus, the disc-like base it with the sprue members I2 and I1 and pin I l with the wax pattern I!) thereon is placed on the base 24 of the casting. The flask with its lower and upper sections 2| and 22, respectively, is positioned over the member l2. The clamping plate 21 is then mounted on the posts 2 5 and laid on the upper edge of the upper section 22. The screws 29 are then set upon to clamp the sections in position and prevent displacement thereof. Investment material 46 is then poured into the lower section 2| to or approximately to the upper ed thereof and tapped leaving a portion of the wax pattern projecting above said investment material. A coating of separating material may then be applied to the upper surface of the investment material to facilitate separation of the flask sections. The upper section-22 is then filledtwith investment material in the same manner. The investment material is then permitted to harden. The mold is then placed in boiling water and the wax is melted out. The two sections are separated, and the pin it and sprue member 11 removed leaving the sprue sleeve 12 embedded in the investment and forming a cavity or mold in the investment material in section 22 shaped like the pattern In and leaving a chamber inside the sleeve 12 connected by a gate passage or sprue shaped like the neck I 8 of the sprue member H.

The flask is thus preparedto receive the denturematerial.

The flask is next positioned on the base 240i the. casting in an inverted position, thatis, the section 2l-with the member l2 embedded therein on the top and the section'22 ;onthe bottom. The clamping plate is then positioned onthe posts. 29 and the flask clamped in position on saidbase. The. mold is then slightlyhand packed withsuitable plastic. denture material. A pressure device is then mounted on the casting for processing.

Whensufiicient pressure has beenapplied, the entire. apparatus is placed in a hot. bath, oven, furnace, or the like whereupon theplastic hardens or sets while pressure is retained thereon,

After, processing the casting, it is allowed to cool. The sections. of the flask are then separated bya suitable tool. The restoration is then removedfrom the investment and cleaned.

The sprue forming member 12 is an importantfeature of the present invention as in addition to forming a sprue in the investment, it also provides means for supporting the pattern in proper position within the soft investment until it hardens.

Theflange portion l l'of'the member 12 and the plate 21 seals the investment in the flask du the processing. This member I2 also keeps the acrylic clean and presents particles of investment from being forced into the mold during processing. It also eliminates the necessity of a protective coating. as in the case where the chamber is made of investment material, and furthermore.

4 it is so shaped that it facilitates the removal of the surplus plastic material.

I claim:

1. In apparatus of the character described,

cavity and sprue forming devices consisting of a I hollow metal cylindrical member having a restricted opening at one end, a cylindrical member inside of said hollow member and having a central passage and arestricted neck portion projecting outwardly through said restricted opening, a pin detachably mounted in said passage and projecting outwardly thereof and a wax pattern on the projecting end of said pin.

2. In apparatus of the character described, a disc member having a central opening, a sectional hollow flask supported on said disc member above said opening for receiving investment material, an outer hollow cylindrical member on said disc member abovesaid opening and extending inwardly of the flask, an inner cylindrical member extending through. the opening insaid disc member and. into the. interior. of said, outer. cylindrical member, saidinner. cylindrical member having a centralpassage and a neck portion projecting outwardly of said. outer member, a pin detachably mounted. in said central passage and projecting outwardly thereof and awax pattern on the projectingend of said pin.

IRVING I-IORDES.

REFERENQES CITED The following references are of recordiinthe file of this patent:

UNITED STATES PATENTS 

